No, you should not put a Pyrex dish directly into a slow cooker. While Pyrex dishes are designed to be oven-safe and can withstand high temperatures, they are not meant to be used directly on the heat source of a slow cooker or any stovetop.
The slow cooker's heating element, whether at the bottom or along the sides, can create direct contact with the Pyrex dish, causing it to crack or shatter due to sudden temperature changes. Pyrex is not designed to handle direct heat from a stovetop or other heating elements that slow cookers use.
Instead, when using a slow cooker, it's best to use the ceramic insert that typically comes with the appliance. The ceramic insert is designed to withstand the low and slow cooking temperatures of a slow cooker and is safe to use with the appliance. It provides even heating and helps prevent the food from sticking to the sides.
If you want to use your Pyrex dish to cook something in the slow cooker, you can place the Pyrex dish inside the slow cooker, on top of the ceramic insert, creating a water bath setup. This method can work well for certain dishes, but it's essential to ensure that the Pyrex dish doesn't touch the sides of the slow cooker and that there's enough water in the slow cooker to prevent the dish from drying out or cracking. However, always check the manufacturer's recommendations for both the slow cooker and the Pyrex dish to ensure you're using them correctly and safely.